1xx Informational
101 Switching Protocols
The server is switching to the protocol the client asked for in `Upgrade`.
What causes it
- A WebSocket handshake succeeded — this is the response to `Upgrade: websocket`.
- An HTTP/1.1 to HTTP/2 upgrade over cleartext (h2c).
How to fix it
- Nothing to fix on a successful WebSocket connection.
- If you expected 101 and got 200, an intermediary stripped the `Upgrade` header — check the proxy configuration.
At a glance
- Class
- 1xx Informational
- Reference
- RFC 9110 §15.2.2
- Standardised
- Yes
- Retry the request?
- No — fix the request